The present application is based on Japanese Priority Document 2000-257238 filed Aug. 28, 2000, the content of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to an ink jet printer which performs printing by discharging ink supplied from nozzle head ink tank having plural ink jet nozzles from selected ink jet nozzles, on a print medium.
2. Discussion of the Background
Conventionally known is a line type ink jet printer which performs printing at a greatly-improved printing speed in comparison with a so-called serial type ink jet printer and performs continuous print operation on a large number of print sheets. This line type ink jet printer can perform continuous printing on, e.g., 500 or more sheets.
In the continuous printing on a large number of print sheets, if only an unincreasable-sized ink cassette (i.e. a small ink cassette) is used as in the case of the conventional serial type ink jet printer where the size of the ink cassette cannot be increased due to a reciprocating movement in a line direction, the ink becomes short.
In the ink jet printer that performs continuous print operation on e.g. 500 or more print sheets, a removable large-capacity ink cartridge is provided, and ink is supplied from the ink cartridge to the ink tank whenever necessary, thereby frequent ink cassette change as in the case of the conventional small ink cassette is unnecessitated and continuous print operation for a long period is realized.
In addition, in this ink jet printer, a removable waste ink tank is provided in a fixed position, and upon maintenance of a nozzle head, ink discharged from the nozzle head is collected into the waste ink tank.
In this large-capacity line type ink jet printer, attachment of ink tank and piping are complicated, assembly thereof is troublesome and the number of processes is large. Accordingly, the ink tank cannot be easily changed. If the printer is used for a long period without changing the ink tank, impurities such as dirt mixed in ink supplied from the ink cartridge to the ink tank and chemical compound of the ink itself (hereinbelow referred to as xe2x80x9cimpuritiesxe2x80x9d) are deposited on the bottom of the ink tank.
As the impurities supplied from the ink tank to the nozzle head cause clogging in the nozzle head, the conventional ink jet printers have various arrangements to prevent the entry of the impurities into the nozzle head.
As an example of arrangement to prevent the entry of the impurities into the nozzle head, an ink supply port from the ink tank to the nozzle head is provided in a position higher than the bottom surface of the ink tank such that the impurities are deposited in a predetermined area. In this case, the impurities reach the supply port in time and the impurities are supplied to the nozzle head. To prevent this inconvenience, the capacity of the ink tank may be increased so as to increase the impurity depositing area. However, if the capacity of the ink tank is increased, the ink jet printer itself is enlarged. Therefore, this arrangement cannot be the best solution.
Further, as another arrangement to prevent the entry of the impurities into the nozzle head, a filter is provided inside the ink tank. However, in this case, as the impurities are deposited inside the filter, the inside space of the filter is filled with the impurities in time, and ink supply to the nozzle head might be disturbed.
Accordingly, an object of the present invention is to provide an ink jet printer which reliably prevents clogging in a nozzle head due to impurities.
The object of the present invention is achieved by the novel ink jet printer head of the present invention.
According to the novel ink jet printer of the present invention, a discharge port formed in the bottom surface of ink tank is connected by a connecting member to a waste ink tank to collect waste ink produced upon nozzle head maintenance, and a part of the connecting member is freely opened/closed by a valve.
Another aspect of the novel ink jet printer head of the present invention, the discharge port formed in the bottom surface of ink tank is connected by connecting means to waste ink tank for collecting waste ink produced upon nozzle head maintenance, and a part of the connecting means is freely opened/closed by a valve.